Materials, textures and how they relate to models before/after render
You got most everything right but there are a few misconceptions there.
Model
A model is the geometry giving shape to a 3D object, it is often of Mesh type but may be also composed of other geometry types, like Curves, Text Objects, or less commonly in Blender NURBS. It may also comprehend other animation related data like rigging, shape keys, and armatures.
The formats you speak of have nothing to do with models themselves, though they serve as way to export them. They are mostly interface file formats useful for transferring data between different applications, Blender does import and export most of them, but to faithfully save your data you must exclusively save in the native .blend file.
Texture
Textures are for the most part regular 2D images as in jpeg, png, tiff, tga, EXR image files. They are just a name for an image that will be controlling a property of a material, it is not a file format that contains &quot;1+&quot; images, it is an image. They simply describe color information, they hold no information regarding surface properties of an object themselves, and can't be used alone for the most part, but can however through a material serve various purposes like provide actual diffuse (visible) color of a material, or other surface properties like roughness (bump or displacement maps), shininess (glossiness or reflectivity), emission, and many other properties.
There are two main types of textures, actual image textures, as described above, using an image file, or procedural ones, generated by the rendering engine (generally can't be exported or used elsewhere outside the source program).
Material
A material is the collection of image textures, procedural textures, shaders, and surface/volume properties that describes the final appearance of the surface. It may include reflectivity, lighting, color and/or volume information. Materials can under certain circumstances be baked into a &quot;static representation&quot; of the surface for export, but are otherwise for the most part not exportable
A material can use any number of textures or none at all, and an object can have any number of materials (except for certain game engines). Materials are assigend to objects using Material Slots but only one can be assigned per face at each time. Of course using too many textures and/or materials may have a negative impact over performance of a scene or rendering.
Rendering
Rendering Is generally used to refer to the process of transforming a Scene (composed of 3D models with Materials) into a 2D image (like taking a picture with a camera). The process of transforming materials into textures, although also achieved through the same rendering process, is generally referred to specifically as Baking. Just to be clear, baking obligatorily involves rendering, but rendering doesn't necessarily require baking.